When you use the word absolute, you are describing a checkpoint.
As that is the only way to absolutely guarantee no changes occur.

Anything before a checkpoint is now locked in stone forever.
Anything after still holds a potential for change, no matter how unlikely or how small the possibility due to a strong consensus.

Checkpoint Servers cause centralization and grant control to the manager of the checkpoint server, since they can determine short term changes in the blockchain path.

Program coded checkpoints are usually a few weeks old, and require all clients constantly update their client to match.

The Most effective Checkpoint that remains decentralized is a rolling checkpoint, that the wallet client automatically refuses any reorganizations to the blockchain past a hard coded block #.
Example: Anything after 24 hours of blocks will refuse to reorganization at the client level.
This grants absolute finality with no worries of centralization.
This way the coin's normal consensus chooses it's path , and the rolling checkpoint guarantees it.

The one potential flaw is a rolling checkpoint, is if an attacker can control enough of the consensus to fork the chain right at the rolling checkpoint and split the network into two forks, that would be a major headache, but if the attacker could do that , he be a major problem anyway as he could double-spend every few hours anyway regardless of the rolling checkpoint.